I have a problem.
I made a project in vs2005 c# for intranet.
I generated a user login entry record and stored this in csv file.
I used three fields in csv file like username, date time, visited page name.
All functionality is working fine here but not working on client side.
Project is running from IIS and have checked the permission for iis users.

What's the problem? All you said is that is works fine in dev "but on client side." What does that mean? Just a guess, but I am guessing your file is not getting created. This would be due to security permissions. Find the account that is running the application pool and grant that user permissions to read/write to the folder you want.